Phytochemicals

Phytochemicals are bioactive, non-nutrient compounds naturally produced by plants as part of their secondary metabolism, primarily serving protective functions for the plant such as defense against pathogens, ultraviolet radiation, and herbivory. Thousands of phytochemicals have been identified in edible plants, and they are broadly grouped into major classes including polyphenols (e.g., flavonoids, phenolic acids, stilbenes, lignans), carotenoids, glucosinolates, phytosterols, organosulfur compounds, and alkaloids.

Although not classified as essential nutrients, phytochemicals are widely studied for their biological activities in humans — including antioxidant, anti-inflammatory, immunomodulatory, neuroprotective, and endocrine-modulating effects — mediated in part through interactions with the gut microbiota, cellular signaling pathways, and gene expression.

Dietary intake of phytochemicals through fruits, vegetables, whole grains, legumes, nuts, seeds, herbs, spices, tea, coffee, and cocoa is associated with reduced risk of chronic diseases and is increasingly examined for its influence on cognition, mood, and mental health.